Semiconductor devices typically include gaps that have been filled with silicon, which may form constituent parts of various electronic devices. The fill may include depositing a layer of silicon on side and bottom surfaces of the gaps, with the layer filling in the gap from the sides and bottom as it grows.
The growth of the layer may not be completely uniform, however, causing voids, such as seams, to form in the interior of the filled gap. In some cases, these voids may be caused by the deposition process, in which silicon may deposit at a higher rate at the top of the gap than at the bottom, thereby causing the top of the gap to close up first, leaving the voids in the interior of the gap or the nucleation on the bottom or side of the gap may be incomplete causing voids in the bottom or side of the gap.
FIG. 1 shows a cross-section of a gap filled with a deposited silicon film. As seen in the region 1 at the center of the cross-section, a void such as a vertically-elongated seam is present. Further, in the region 2, another void is present closer to the structure. Such voids can adversely impact the electronic devices formed by the filled gap in between fins 3 composing the structure.
Accordingly, there is a need for processes for forming silicon filled gaps, while leaving no or nearly no voids in the gaps.